This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. TLR4 is a 100 kDa transmembrane glycoprotein that belongs to the Toll-Like Receptor family of pathogen pattern recognition molecules. In complex with another protein, MD2 (25 kDa), it responds to lipopolysaccharides binding at the outer surface of the cell membrane and initiates intracellular signaling cascades. We started cryoEM of TLR4/MD-2 complex at UTMB but the study was interrupted by hurricane Ike in 2008. We are using the NCMi facility for data collection.